1. Field of the Invention
The invention relates to alkoxylation products having terminal hydroxyl groups which are blocked with glycerine ether radicals. These products are highly biodegradable and are low foaming. The invention further relates to a process for their preparation.
2. Description of the Prior Art
In our mechanized societies, automatic washing processes are primarily used for cleaning dishes and other objects made of glass, china, ceramics or metal. Dishwashing detergents containing specific surface-active compounds are used for this purpose. These detergents must be low foaming for proper functioning of the dishwashers. Too much foaming, caused by the movement of the washing fluid in the machines, results in problems since the foam reduces the cleaning power of the washing fluid being sprayed upon the materials to be cleaned and may cause the machine to overflow.
Compounds generally referred to as ethylene oxidepropylene oxide block polymers, as described in U.S. Pat. No. 2,674,619, represent an important class of nonionic surfactants used to reduce the foaming of automatic dishwashing detergents. These surfactants are characterized by their low foaming properties and good dispersing capacity. However, they also have a low wetting capacity and their biodegradability is far below 80 percent.
Low-foaming nonionic surfactants which are produced by reaction of a maximum of 1.5 moles butylene oxide with a higher alkanol ethoxylate containing 4 to 10 moles of ethylene oxide per higher alkanol are described in German Published Application No. 1,814,439. It has, however, been determined that these surfactants are not yet satisfactory with respect to their foam inhibiting properties, especially when the washing fluid contain high protein content.
It is well known that the formation of foam can be inhibited by the effects of the higher alkylene oxides such as propylene and/or butylene oxide upon ethoxylated alcohols. This effect is increased as the alkylene oxide content is increased. However, increasing the alkylene oxide content reduces the biodegradability. Thus, for instance, the report of the Sixth International Congress for Surface-Active Materials of Sept. 11-15, 1972 in Zurich by W. K. Fischer of the Henkel KGaA Company (see Vol. 3, page 746, and FIG. 9) explains that ethoxylated C.sub.12 to C.sub.20 fatty alcohols with 2 moles of butylene oxide as end groups have a biodegradability which the bottle test listed in this literature reference indicates to be absolutely unsatisfactory.
Although it is known from the monograph, Catalysts, Surfactants and Mineral Oil Additives, page 149, column 2, paragraph 2, edited by J. Falbe and U. Hasserodt, (George Thieme Publishers, Stuttgart 1978), that alkoxylation groups may be reacted with glycidyl ethers to prepare products which are useful in detergents because of their low foaming tendencies, this reference says nothing about specific representatives of this product class and no statements are made concerning their biodegradability.
Such compounds which are the propoxylation products of long-chained alcohols which were reacted with a long-chained glycidyl ether, are also described in German Published Application No. 2,225,318. However, they are not water soluble and are used as defoamers in paper coating materials. Moreover, these compounds are not biodegradable.